A selected set of trinucleotide simple sequence repeat markers for soybeancultivar identification

Soybean [Glycine max (L.) Merr.] cultivars are described for purposes of Pl ant Variety Protection (PVP) by standard pigmentation and morphological tra its. However, many commercial soybeans arise from a limited number of elite lines and ave often indistinguishable based on these traits. A system base d an DNA markers could provide unique DNA profiles or fingerprints of culti vars. Simple Sequence Repeat (SSR) or microsatellite allele size profiling is used in human forensics to provide unique DNA fingerprints of an individ ual. Allele sizing technologies are well established and can be readily use d to size SSR alleles from any organism. The purpose of the work presented here was to select and evaluate a small set of trinucleotide SSR markers wi th maximum reliability and repeatability that would provide a high level of discriminatory power to distinguish soybean genotypes. A total of 48 fluor escently labelled SSR primer sets was used to amplify genomic DNA of the 35 ancestors of N American soybeans as well as a diverse group of elite N. Am erican soybean cultivars. Only loci with allele size ranges that showed no overlap in size over a series of analyses and in which adjacent alleles dif fered by at least three basepairs were maintained for further statistical a nalysis via a clustering procedure. Cluster analysis was performed on the r emaining loci and resulted in the identification of a subset of 13 loci, fr om 12 different linkage groups, that easily produced unique SSR allele size profiles for each of the 66 elite N. American soybean cultivars. This set of 13 loci wets used to characterise four independent sets of elite cultiva rs that were selected based upon identical maturity morphological, and pigm entation traits. Based upon these analyses, all cultivars could be distingu ished using the set of 13 selected SSR loci. This set of loci is proposed a s ct standard set for use in DNA profiling of soybean cultivars for purpose s of obtaining PVP.